#include<fstream>
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
long long N,nr,acum=0,ant=0;
int main()
{
    fin>>N;
    for(int i=1;i<=N;i++)
{ fin>>acum;
  if(acum>ant) nr+=acum-ant;
  ant=acum;
}
fout<<nr;
    
    
    
    
    
    
   fin.close();
   fout.close();   
   return 0; 
}